Zhongbin Zhuang

Isolated Single Iron Atoms Anchored on N-Doped Porous Carbon as an Efficient Electrocatalyst for the Oxygen Reduction Reaction

The development of low-cost, efficient, and stable electrocatalysts for the oxygen reduction reaction (ORR) is desirable but remains a great challenge. Herein, we made a highly reactive and stable isolated single-atom Fe/N-doped porous carbon (ISA Fe/CN) catalyst with Fe loading up to 2.16u2005wtu2009%. The catalyst showed excellent ORR performance with a half-wave potential (E1/2 ) of 0.900u2005V, which outperformed commercial Pt/C and most non-precious-metal catalysts reported to date. Besides exceptionally high kinetic current density (Jk ) of 37.83u2005mVu2009cm-2 at 0.85u2005V, it also had a good methanol tolerance and outstanding stability. Experiments demonstrated that maintaining the Fe as isolated atoms and incorporating nitrogen was essential to deliver the high performance. First principle calculations further attributed the high reactivity to the high efficiency of the single Fe atoms in transporting electrons to the adsorbed OH species.

Ultrasmall Cu7S4@MoS2 Hetero‐Nanoframes with Abundant Active Edge Sites for Ultrahigh‐Performance Hydrogen Evolution

Increasing the active edge sites of molybdenum disulfide (MoS2 ) is an efficient strategy to improve the overall activity of MoS2 for the hydrogen-evolution reaction (HER). Herein, we report a strategy to synthesize the ultrasmall donut-shaped Cu7 S4 @MoS2 hetero-nanoframes with abundant active MoS2 edge sites as alternatives to platinum (Pt) as efficient HER electrocatalysts. These nanoframes demonstrate an ultrahigh activity with 200u2005mAu2009cm(-2) current density at only 206u2005mV overpotential using a carbon-rod counter electrode. The finding may provide guidelines for the design and synthesis of efficient and non-precious chalcogenide nanoframe catalysts.

MOF-Derived Formation of Ni2P–CoP Bimetallic Phosphides with Strong Interfacial Effect toward Electrocatalytic Water Splitting

Bimetallic phosphides have attracted research interest for their synergistic effect and superior electrocatalytic activities for electrocatalytic water splitting. Herein, a MOF-derived phosphorization approach was developed to produce Ni2P-CoP bimetallic phosphides as bifunctional electrocatalysts for both hydrogen and oxygen evolution reactions (HER and OER). Ni2P-CoP shows superior electrocatalytic activities to both pure Ni2P and CoP toward HER and OER, revealing a strong synergistic effect. High-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy elemental mapping analysis show that, in the sample Ni2P-CoP, the Ni2P and CoP nanoparticles with an average particle size 10-20 nm were mixed closely on the nanoscale, creating numerous Ni2P/CoP interfaces. By comparison with the sample Ni2P+CoP, in which seldom Ni2P/CoP interfaces exist, we documented that the Ni2P/CoP interface is an essential prerequisite to realize the synergistic effect and to achieve the enhanced electrocatalytic activities in Ni2P-CoP bimetallic phosphides. This finding is meaningful for designing and developing bicomponent and even multicomponent electrocatalysts.

Design of ultrathin Pt-Mo-Ni nanowire catalysts for ethanol electrooxidation

Researchers design ultrathin Pt-Mo-Ni NWs as cost-effective, active, and durable electrocatalysts. Developing cost-effective, active, and durable electrocatalysts is one of the most important issues for the commercialization of fuel cells. Ultrathin Pt-Mo-Ni nanowires (NWs) with a diameter of ~2.5 nm and lengths of up to several micrometers were synthesized via a H2-assisted solution route (HASR). This catalyst was designed on the basis of the following three points: (i) ultrathin NWs with high numbers of surface atoms can increase the atomic efficiency of Pt and thus decrease the catalyst cost; (ii) the incorporation of Ni can isolate Pt atoms on the surface and produce surface defects, leading to high catalytic activity (the unique structure and superior activity were confirmed by spherical aberration–corrected electron microscopy measurements and ethanol oxidation tests, respectively); and (iii) the incorporation of Mo can stabilize both Ni and Pt atoms, leading to high catalytic stability, which was confirmed by experiments and density functional theory calculations. Furthermore, the developed HASR strategy can be extended to synthesize a series of Pt-Mo-M (M = Fe, Co, Mn, Ru, etc.) NWs. These multimetallic NWs would open up new opportunities for practical fuel cell applications.

Atomically Dispersed Copper–Platinum Dual Sites Alloyed with Palladium Nanorings Catalyze the Hydrogen Evolution Reaction

Designing highly active catalysts at an atomic scale is required to drive the hydrogen evolution reaction (HER). Copper-platinum (Cu-Pt) dual sites were alloyed with palladium nanorings (Pdu2005NRs) containing 1.5u2005atomu2009% Pt, using atomically dispersed Cu on ultrathin Pdu2005NRs as seeds. The ultrafine structure of atomically dispersed Cu-Pt dual sites was confirmed with X-ray absorption fine structure (XAFS) measurements. The Pd/Cu-Ptu2005NRs exhibit excellent HER properties in acidic solution with an overpotential of only 22.8u2005mV at a current density of 10u2005mAu2009cm-2 and a high mass current density of 3002u2005Au2009g-1(Pd+Pt) at a -0.05u2005V potential.

Single Tungsten Atoms Supported on MOF-Derived N-Doped Carbon for Robust Electrochemical Hydrogen Evolution

Tungsten-based catalysts are promising candidates to generate hydrogen effectively. In this work, a single-W-atom catalyst supported on metal-organic framework (MOF)-derived N-doped carbon (W-SAC) for efficient electrochemical hydrogen evolution reaction (HER), with high activity and excellent stability is reported. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption fine structure (XAFS) spectroscopy analysis indicate the atomic dispersion of the W species, and reveal that the W1 N1 C3 moiety may be the favored local structure for the W species. The W-SAC exhibits a low overpotential of 85 mV at a current density of 10 mA cm-2 and a small Tafel slope of 53 mV dec-1 , in 0.1 m KOH solution. The HER activity of the W-SAC is almost equal to that of commercial Pt/C. Density functional theory (DFT) calculation suggests that the unique structure of the W1 N1 C3 moiety plays an important role in enhancing the HER performance. This work gives new insights into the investigation of efficient and practical W-based HER catalysts.

Ultrathin Palladium Nanomesh for Electrocatalysis

An ordered mesh of palladium with a thickness of about 3u2005nm was synthesized by a solution-based oxidative etching. The ultrathin palladium nanomeshes have an interconnected two-dimensional network of densely arrayed, ultrathin quasi-nanoribbons that form ordered open holes. The unique mesoporous structure and high specific surface area make these ultrathin Pd nanomeshes display superior catalytic performance for ethanol electrooxidation (mass activity of 5.40u2005Amu2009g-1 and specific activity of 7.09u2005mAu2009cm-2 at 0.8u2005V vs. RHE). Furthermore, the regular mesh structure can be applied to support other noble metals, such as platinum, which exhibits extremely high hydrogen evolution reaction (HER) activity and durability.

Fe Isolated Single Atoms on S, N Codoped Carbon by Copolymer Pyrolysis Strategy for Highly Efficient Oxygen Reduction Reaction

Heteroatom-doped Fe-NC catalyst has emerged as one of the most promising candidates to replace noble metal-based catalysts for highly efficient oxygen reduction reaction (ORR). However, delicate controls over their structure parameters to optimize the catalytic efficiency and molecular-level understandings of the catalytic mechanism are still challenging. Herein, a novel pyrrole-thiophene copolymer pyrolysis strategy to synthesize Fe-isolated single atoms on sulfur and nitrogen-codoped carbon (Fe-ISA/SNC) with controllable S, N doping is rationally designed. The catalytic efficiency of Fe-ISA/SNC shows a volcano-type curve with the increase of sulfur doping. The optimized Fe-ISA/SNC exhibits a half-wave potential of 0.896 V (vs reversible hydrogen electrode (RHE)), which is more positive than those of Fe-isolated single atoms on nitrogen codoped carbon (Fe-ISA/NC, 0.839 V), commercial Pt/C (0.841 V), and most reported nonprecious metal catalysts. Fe-ISA/SNC is methanol tolerable and shows negligible activity decay in alkaline condition during 15u2006000 voltage cycles. X-ray absorption fine structure analysis and density functional theory calculations reveal that the incorporated sulfur engineers the charges on N atoms surrounding the Fe reactive center. The enriched charge facilitates the rate-limiting reductive release of OH* and therefore improved the overall ORR efficiency.

Promoting the methanol oxidation catalytic activity by introducing surface nickel on platinum nanoparticles

High performance methanol oxidation reaction (MOR) catalysts are critical to the performance of attractive, direct methanol fuel cells. Here, we use surface controlled PtNi alloy nanoparticles as model catalysts to study the MOR mechanism and give further guidance to the design of new high performance MOR catalysts. The enhanced MOR activity of PtNi alloy was mainly attributed to the enhanced OH adsorption owing to surface Ni sites. This suggests that the MOR undergoes the Langmuir–Hinshelwood mechanism, whereby adsorbed CO is removed with the assistance of adsorbed OH. Within the PtNi catalyst, Pt provides methanol adsorption sites (in which methanol is converted to adsorbed CO) and Ni provides OH adsorption sites. The optimized Pt–Ni ratio for MOR was found to be 1:1. This suggests that bifunctional catalysts with both CO and OH adsorption sites can lead to highly active MOR catalysts.

Photocatalytic hydrogenation of nitroarenes using Cu1.94S-Zn0.23Cd0.77S heteronanorods

Catalytic hydrogenation is an important process in the chemical industry. Traditional catalysts require the effective cleavage of hydrogen molecules on the metal-catalyst surface, which is difficult to achieve with non-noble metal catalysts. In this work, we report a new hydrogenation method based on water/proton reduction, which is completely different from the catalytic cleavage of hydrogen molecules. Active hydrogen species and photo-generated electrons can be directly applied to the hydrogenation process with Cu1.94S-Zn0.23Cd0.77S semiconductor heterojunction nanorods. Nitrobenzene, with a variety of substituent groups, can be efficiently reduced to the corresponding aniline without the addition of hydrogen gas. This is a novel and direct pathway for hydrogenation using non-noble metal catalysts.